• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3D
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• pp.499-509
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• 2006

Precast concrete deck has many advantages comparing with the in-situ concrete deck, and has been successfully applied to replacement of the deteriorated decks and to the newly constructed highway bridges in domestic region. In order to apply the precast decks into the railway bridges, however, differences of the load characteristics between the highway and the railway should be properly taken into account including the train load, longitudinal force of the continuous welded rail, acceleration or braking force, temperature change and shrinkage. Proper level of the longitudinal prestress of the tendons that can ensure integrity of the transverse joints in the deck system is of a primary importance. To this aim, the longitudinal tensile stresses induced by the design loads are derived using three-dimensional finite element analyses for the frequently adopted PSC composite girder railway bridge. The effect of the temperature change is also investigated considering the design codes and theoretical equations in an in-depth manner. The estimated proper prestress level to counteract those tensile stresses is above 2.4 MPa, which is similar to the case of the highway bridges.

• Journal of the Korean Society of Child Welfare
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• no.53
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• pp.1-23
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• 2016

With using a subsample of 1,373 poor single mothers and their children from the Fragile Families and Child Wellbeing study, the present study examined the associations among mothers' economic hardship, depressive symptoms, and parenting stress, child abuse and neglect, and their children's behavior problems, delinquency, and social skill. These families were tracked through follow-up interviews at the time of birth, and when the children were three, five, and nine years old. The results indicated that mothers' economic hardship, depressive symptoms, and parenting stress were significant predictors to determine their children's abuse and neglect. Findings also suggest that higher levels of child abuse and neglect are positively associated with more behavior problems and delinquency, and negatively associated with social skills. Further discussions include policy and services to prevent child abuse and neglect and to alleviate mothers' financial difficulties, depression, and parenting stress.

• Korean Journal of Culture and Social Issue
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• v.22 no.3
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• pp.411-430
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• 2016

The purpose of the present study was to examine psychological consequences of indirect trauma exposure through the disaster news. Participants(N=439) completed some self-report questionnaires such as Posttraumatic Risk Checklist(PRC), Impact of Event Scale-Revised(IES-R), and Multidimensional Fear of Death Scale(MFODS) at 68.11(±18.47) days after the Sewol ferry disaster. The data were analyzed with structural equation modeling by AMOS 23.0 program. The results showed that fear of death and periand post-traumatic crisis factors mediated the association of news exposure immediately after disaster and posttraumatic stress symptoms. Findings in this study indicated that news exposure immediately after disaster influenced fear of death which led to the peri- and post-traumatic crisis, and these crisis factors increased posttraumatic stress symptoms. Finally, limitations of this study and suggestions for future study were discussed.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.1076-1079
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• 2011

본 연구는 일개 광역시 주민들 4000명을 대상으로 일반적 특성, 건강행태 관련 특성, 신체비활동 정도를 조사하여 신체비활동의 유발요인에 대해 알아보고자 시행되었다. 그 결과를 요약하면 다음과 같다. 걷기운동 미실천 수준의 경우 연령, 교육수준, 의료보장, 직업, 기초생활수급유무, 독감 예방접종, 체중조절시도, 고위험음주, 스트레스 인지정도, 지역사회 운동프로그램참여, 운동시설의 접근성이, 중등도 이상의 운동 미실천의 경우, 성별, 연령, 월 소득, 가구소유, 건강검진 여부, 체중 조절 시도, 현재 흡연 여부, 지역 사회 운동 프로그램참여가 통계적으로 유의했으며, 이 변수들을 이용하여 신체비활동 수준을 결과변수로 하는 로지스틱 회귀분석을 시행하여, 걷기운동의 경우 20대에 비해서 30대가 1.46배, 40대가 1.57배 미실천률이 높고, 사무직이 전문행정관리직에 비해 1.37배, 체중조절을 시도하지 않은 군이 한 군에 비해 1.70배, 스트레스를 많이 느낀 군이 안 느낀 군에 비해 1.58배, 조금 느낀 군에 비해 1.38배, 운동시설 접근성이 어려운 군이 쉬운 군에 비해 1.75배정도 높은 것으로 분석되었고, 중등도 이상 운동의 경우 여자의 경우 남자에 비해 미실천율이 1.74배, 체중조절시도를 안한 군이 한 군에 비해 1.63배, 지역사회운동프로그램참여 안한 군이 한 군에 비해 2.36배 높은 것으로 나타났다. 고령화 사회로 가고 있는 현 상황에서 여러 가지 만성질환이 대두되고 있고, 이에 따른 신체활동의 중요성이 대두되고 있다. 하지만 우리나라의 경우 신체활동 실천율이 낮은 것이 현실이다. 신체활동의 실천율을 향상시키기 위해서는 신체비활동 결정짓는 요인들에 대해 우선 파악해야 한다. 분석결과 가장 차이가 나는 것은 운동시설의 접근성과 지역사회운동프로그램의 불참군에서 가장 신체비활동이 큰 것으로 파악되었다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.6
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• pp.519-525
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• 2023

The human brain constantly emits electrical impulses, which is called brain waves, and brain waves can be defined as the electrical activity of the brain generated by the flow of ions generated by the biochemical interaction of brain cells. There is a study that emotion is one of the factors that can cause stress. Brain waves are the most used in the study of emotions. This paper is a study on whether emotions affect stress, and showed two images of fear and joy to four experimenters and divided them into three stages before, during, and after watching. As a measurement tool, brain waves at the positions of Fp1 and Fp2 were measured using the NeuroBrain System, a system that can automate brain wave measurement, analysis, brain wave reinforcement, and suppression training with remote control. After obtaining the brain wave data for each emotion, the average value was calculated and the study was conducted. As for the frequency related to stress, the values of Alpha and SMR, Low Beta, and High Beta were analyzed. Brainwave analysis affects stress depending on the emotional state, and "fear" emotions cause anxiety by raising Beta levels, resulting in higher Mind Stress levels, while "joy" emotions lower Beta levels, resulting in a significant drop in Mind Stress.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.3
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• pp.287-293
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• 2022

Gray hair is a representative sign of aging. Intrinsic aging, stress, and the external environment cause hair graying. Stress is known to be a major factor in the early onset of hair graying. We previously found that Pueraia lobata root extract (PLRE) can prevent hair graying by promoting melanin formation. However, it remains unknown whether PLRE can prevent hair graying induced by conditions of stress. In this study, we confirmed the effect of PLRE on stress-induced hair graying. A reporter cell line was newly constructed to confirm the expression of microphthalamia-associated transcription factor (MITF), the main transcription factor for melanin production. MITF expression and melanin pigmentation were reduced in human hair follicle tissue treated with the stress hormone cortisol or H₂O₂ to induce oxidative stress. PLRE treatment restored MITF expression and increased the amount of melanin pigment in the hair follicle. The expression of Tyrosinase related proteins-2 (TRP-2), a melanin synthesis enzyme in the hair follicle, also increased. In conclusion, PLRE can effectively prevent the inhibition of melanin synthesis by stress hormones and oxidative stress.

• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.851-860
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• 2022

Catholic nuns are under a lot of role stress while living as a monk, which leads to psychological burnout, causing negative effects. This study confirmed which sub-factors of the role stress of Catholic nuns has a greater effect on psychological burnout, and analyzed whether resilience has a moderating effect on psychological burnout. As a result of a mail survey of 234 catholic nuns, first, role stress could be confirmed according to the period of catholic nuns' life in the capital and the roles of internal and external apostles. In particular, when the life of the capital was less than 20 years, they felt different from the role ambiguity. Second, it was found that the role stress of catholic nuns had an effect on psychological burnout, and role ambiguity, role conflict, and role all had an effect on psychological burnout. In particular, role ambiguity was found to have the greatest effect, causing greater psychological burnout of role ambiguity than role. Third, in the relationship between role stress and psychological burnout, resilience had a moderating effect This study suggests that reducing the role ambiguity of nuns is the most important, and that it is necessary to improve resilience as a way to reduce psychological burnout. Above all, it is meaningful in that it targets nuns who are difficult to access easily.

• 한국노년학
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• v.30 no.3
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• pp.793-802
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• 2010

The purpose of this study was to examine the influence of extreme heat on muscle function and muscle injury marker in elderly women. The subjects of this study were eight post-menopausal elderly women without any metabolic disease. All eight subjects were asked to perform the knee joint isokinetic exercise using isokinetic equipment (cybex) in the laboratory and experimental temperature within laboratory was adjusted to two conditions: extreme heat temperature(33±0.5℃) and normal temperature(20±0.5℃) maintained in 50±3% humidity conditions. Each experimental exercise was monitored and analyzed the change of HSP70, LDH and CK. Muscular functions (peak torque, total work, percentage of peak torque body weight, fatigue index, average power and total work) were significant differences at exercise between temperatural conditions (p<.05). In extreme heat temperature, muscular injury markers (HSP70, LDH and CK) were increased, threfore resulted in significantly higher than normal temperature(p<.05). These results show that extreme heat temperature can decrease muscle function in elderly women.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.39 no.1
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• pp.31-36
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• 2016

Recently, Live-Virtual-Constructive (L-V-C) integrate training system has proposed as a solution for the problems such as limitation of training areas, increase of mission complexity, rise in oil prices. In order to integrate each training system into the one effectively, we should solve the issue about stress of pilots by the environmental differences between Live and Virtual simulation which could be occurred when each system is connected together. Although it was already examined in previous study that the psychological effects on pilots was occurred by the environmental differences between actual and simulated flights, the study did not include what the causal factors affecting psychological effects are. The aim of this study is to examine which environmental factors that cause pilots' psychological effects. This study analyzed the biochemical stress hormone, cortisol to measure the pilots' psychological effects and cortisol was measured using Enzyme-linked immunoassay (EIA). A total of 40 pilots participated in the experiment to compare the differences in pilots' cortisol response among live simulation, virtual simulation, and the virtual simulation applying three environmental factors (gravity force, noise, and equipment) respectively. As a result, there were significant differences in cortisol level when applied the gravity force and equipment factors to the virtual simulation, while there was no significant difference in the case of the noise factor. The results from this study can be used as a basis for the future research on how to make L-V system by providing minimum linkage errors and design the virtual simulator that can reduce the differences in the pilots' psychological effects.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.4
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• pp.393-397
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• 2020

Shunt reactor, a facility for reactive power compensation, is switched several times a day depending on the load pattern. When the circuitbreaker opens the shunt reactor over-voltage is generated by several factors which degrade the insulating performance of internal parts of the circuit-breaker and cause severe voltage stress on the equipment in the power system. Transient phenomenon occurring during the switching of shunt reactor are available in laboratories that verify the performance of the circuit-breaker by simulating the power system. However, it is difficult to measure the transient phenomenon that occurs during actual operation in actual power system due to many limitations. Therefore, this paper deals with the modeling using EMTP to analyze the reignition and current chopping which causes more severe transient recovery voltage in the small inductive current breaking in actual power systems. In addition, this paper analyzes the main phenomenon that cause circuit-breaker failure in opening shunt reactor using EMTP model.